Slime-pulp thickener



C. ALLEN.

SLIME PULP THICKENER.

APPLICATION FILED OCT. 5. 191a.

Patentd May 11,1920.

UNITED STATES lAIENT OFFICE.

CHARLES ALLEN, or EL Peso, TEXAS.

SLIME-PULP rnrcxnnna.

Specification of Letters fit'ent.

Patented May 11, 1920;

Original application filed June 9, 1917, Serial No. 173,785. Divided andthis application filed. October 5, 1918. Serial No. 256,968.

To all whom it may concern: I

Be it known that I, CHARLES ALLEN, a citizen of the United States,residin at El Paso, in the county of El Paso and tate of Texas, haveinvented new and useful Improvements in Slime-Pulp Thickeners, of whichthe following is a specification.

This invention relates to a device for thickening slime or pulp, andparticularly pertains to a structure similar to that disclosed in myco-pending application entitled, Slime pulp thickener, Serial Number 173,785, filed June 9, 1917, and of which the present application is adivision.

Thickening, which is a partial dcwatering of finely divided solids insuspension, is almost universally used in the treatment of ores by wetmilling processes, and in its every application it is of primeimportance that the degree of thickeningbe uniform, that is, that thedischarge of the thickened slime be always of the same density.Thickeners heretofore used depend upon the volume of pulp fed to thecone or tank for regulation of the size of the discharge orifice. Theresults are very unsatisfactory, inasmuch as the proportion of liquidsto solids in the material discharged varies with the volume of slimepulp fed to'the' thickener.

In the present invention, the volume of slime pulp in the thickener inno manner alters the proportion of liquids tos'olids in the productsdischarged, within the limits of the capacity of the machine. The degreeof thickeningis controlled, and for whatever degree of thickening thedevice is adjusted, that degree of thickening is auto maticallymaintained.

In slime pulp, the finely divided solids move freely without appreciablyaffecting the fluidity by friction among themselves. Such a pulp has theproperties of a liquid so long as the solids are kept in suspension.WVhen the pulp is composed of Water and solid particles of greaterspecific gravity than water, the specific gravity of the pulp increaseswith all increases in the quantity of solids in suspension in the pulp.This pulp may thereforebe considered as a liquid of greater density thanwater. 7

In my invention I employ tw'o connected compartments having in onecompartment a liquid, and in the other a mixture of liquid and solids orpulp. The variations in the density of the pulp,- due to the presencelaunder 1 2 is arranged around the top of'more or less solids insuspension, act to raise and lower the column of liquid, which columnofliquid carries a float operativcly connected to a valve at the bottomof the tank controlling the discharge orifice. When the pulp attains acertain density the valve is automatically openedto permit the dischargeof the thickened pulp through the vmains practically constant. This isthe reverse of the thickeners ordinarily used in which the volume ofthickened slime discharged remains constant while the density of thedischarge varies with the quantity fed into the thickener.

The invention is illustrated by way of example in the accompanyingdrawing in which the figure discloses the complete apparatus, as seen incentral, vertical section.

Referring more particularly to the drawing, the apparatus is shown ascomprising a tank 10 in the shape of an inverted cone having a dischargeorifice 11 at its bottom for carrying off the thickened product. A ofthe tank. for carrying ofli' clear liquid which overflows the rim of thetank. A conduit 18 is provided to supply slime pulp to the center of thetank. The outlet 11 of the tank is indirectly opened and closed by afloat 14 having variable buoyancy due to the application of adjustableweights 15. This ,float is providedwith operable connections 16 whichextend downwardly and engage the and further extends downwardly to alevel below the rim of the tank. This chamber is supplied with clearwater through an in let supply pipe 19. The annular passageway of thechamber 18 is formed with openings in its bottom which are providod withtubular connecting elements 20 extending downwardly and communicatingwith a bell 21. This bell is in the shape of a cone terminating with acylindrical lower portion.

The apex of the cone portion of the bell is in vertical alinement withthe outlet opening of the conduit 13, and is also in concentricalinement with the vertical axis of the tank. The lower opened end ofthe bell is partially closed by means of an inverted conical shell 22,which is held with its base portion in spaced relation to the lowermarginal edge of the bell 21 and allows a limited circulation of liquidthrough this opening to the bell. The downwardly projecting apex 22 ofthe shell 22 is in vertical alinement with the outlet orifice 11, thusthe shell provides a throat of uniform cross section along which thepulp may pass to the orifice. The chamber 18 which communicates with thebell 21 through the passages 20 constitutes one of the connectedcompartments of which the tank with its pulp forms the other arms. Thesetwo compartments or communicating conduits are 'so arranged that ahydrostatic balance is established between the column of clear water onthe one hand and the pulp on the other.

The variations in the density of the pulp outside of the float chamberact to vary the height of the column of water within the chamber, andwill thereby directly produce a raising or lowering of the float, andthrough this action open or close the discharge orifice.

In the present instance the actuating force is the difference in thedensity of the contents of the tank and the contents of chamber 18,which to maintain a hydrostatic balance, raises the surface of theliquid in the conduit containing the liquid of lesser density above thelevel of the surface in the conduit containing the material of greaterdensity. This difference of level is directly proportionate to thedifference in the densities of the liquids. If it is assumed that thetank is filled with water as well as the chamber 18, the vertical lengthof the columns in both cases would be the same; if, without altering thelength of the column, the density of the contents of one liquid columnof the apparatus be increased, say one-tenth, then to maintain ahydrostatic balance, the length of the opposing column must be increasedone-tenth. Applying this tothe device here shown, the portion of thetank 10 above the lower end of the bell 21 will represent one liquidcolumn of the apparatus, and the chamber 18 and the bell 21 with theconnecting elements 20 represent containing the thickened slime, asconsidered from the bottom of the bell as a base and directly inproportion to the excess in density of the contents of the tank overthat of the contents of the float chamber and the associate parts.

Assume this difference in the density of the liquids in the two columnsto be 0.25 and 8 the length of both columns when occupied by a liquid ofthe same density to be 25 inches, then the difference in the length ofthe two columns would be 6.25 inches. To prepare the device foroperation, the cham- 9 ber 18, the bell 21 and the tank 10 are filledwith clear water which may be admitted through the pipe 19. The slimepulp to be thickened is then admitted to the tank through the conduit13, and as the liquid 9 contents of the tank overflow the rim thereof,the thickening process will take place. If, during the operation theliquid contents of'the bell 21 should not remain as free as might bedesired from the solid particles in suspension, this liquid may bereplaced by clear water through the pipe 19 without interrupting theoperation of the apparatus. If desired, there may be a continuous flowof water from the supply pipe 19 into the 1 float chamber.

In order that the condition of the liquid in the chamber 21 may beascertained, a tap pipe X is provided to extend through the side wall ofthe tank and through the hell 1 21. The cone shaped baflie 22 confinesthe downward flow of the thickened slime to an annular space within thetank and prevents a rapid downward movement of the slime directly abovethe discharge orifice 11, thus relieving the slime from objectionableagitation which might produce a suction within the bell 21 to draw theclear water downwardly from the chamber 18, it being desir I able tomaintain the liquid contents of the 1 bell 21 and the chamber 18 insubstantially a state of rest.

Itwill thus be seen that an apparatus is here provided which willautomatically, operate to maintain the slime at a uniform density,saidoperation being dependent upon the foregoing specification thatthese terms include any other liquid or solution employed in practicalmilling operations.

While I have shown the preferred form of my invention as now known tome, it is understood that various changes may be made in thecombination, construction and arrangement of parts without departingfrom the spirit of the invention as claimed.

Having thus described my invention, what I claim and desire to secure byLetters Patent is- 1. In a thickener for slime pulp, a settling tankhaving a controllable orifice for the discharge of thickened material, afluid column in hydrostatic balance with the thickening material andadapted to contain fluid of fixed density whereby variations in thedensity of the thickening material will cause a change in the elevationof the fluid in said column, means actuated by the rise and fall of theheight of the fluid in said column to control the sizes of the dischargeorifice and a cone-shaped baffle member at the bottom of the fluidchamber overlying the discharge orifice for the purpose mentioned. p

2. A thickener for slime pulp, comprising a tank, an orifice at thebottom thereof, a valve for controlling the same, an inverted bellwithin the tank, an annular float chamber above the bell, a centralpassageway through which slime pulp may be fed into the tank, a floatwithin said chamber, operating connections between the float and thevalve, communicating passageways between the bell and the float chamber,whereby clear water positioned within the bell and chamber may stand inhydrostatic balance in relation to the pulp in the surrounding tank andwill thus insure that variation in this hydrostatic balance will affectthe float to accommodate the valve and thereby cause pulp of apredetermined density to be discharged from the tank.

3. A thickener for slime pulp, comprising a tank, an orifice at thebottom thereof, a valve for controlling the same, an inverted bellwithin the tank, an annular float chamber above the bell, a centralpassageway through which slime pulp may be fed into the tank, a floatwithin said chamber, operating connections between the float and thevalve, communicating passageways between the bell and the float chamber,whereby clear water positioned within the bell and chamher may stand inhydrostatic balance in re- I lation to the pulp in the surrounding tankand will thus insure that variation in this hydrostatic balance willaffect the float to accommodate the valve and thereby cause pulp of apredetermined density to be discharged from the tank and an invertedconical shell disposed below the mouth of the bell and spaced inrelation thereto to prevent undue agitation of the liquid within thebell.

4-. A thickener for slime pulp comprising an inverted conical tank, alaunder around the rim thereof, a valve controlled discharge opening inthe apex of said cone, a conical bell positioned within the tank andadapted to receive clear water, an inverted conical shell secured tosaid bell and held in spaced relation therebeneath, an annular floatchamber positioned above the bell and in com- 'munication therewith,said chamber and bell being filled with clear water, a float within saidchamber, means connecting with the float and adapted to control theorifice in the bottom of the tank, whereby variation in the hydrostaticbalance between the pulp within the tank and the clear water within thebell will actuate said orifice controlling mechanism.

5. A thickener for slime pulp, comprising a tank, an orifice at thebottom thereof, a valve for controlling the same, an inverted bellwithin the tank, an annular float chamber above the bell, a centralpassageway through which slime pulp may be fed into the tank, a floatwithin said chamber, oper ating connections between the float and thevalve, communicating passageways between the bell and the float chamber,whereby clear water positioned within the bell and chamber may stand inhydrostatic balance in relation to the pulp in the tank and will thusinsure that variation in this hydrostatic balance will affect the floatto accommodate the valve and thereby cause pulp of a predetermineddensity to be discharged from the tank, and means whereby the water insaid float chamber and inverted bell may be maintained in anuncontaminated condition. In testimony whereof I have hereunto set myhand in the presence of two subscribing witnesses.

CHARLES ALLEN. Witnesses:

O. A. GRITCH'ER, EDMUND SHAW.

